Objects at different depths in the scene of a stereoscopic video sequence will have different displacements, i.e., disparities, in left and right frames of the stereoscopic video sequence, thus creating a sense of depth when the stereoscopic images are viewed on a stereoscopic display. The term disparity refers to the shift that occurs at each pixel in a frame between the left and right images due the different perspectives of the cameras used to capture the two images. The amount of shift or disparity may vary from pixel to pixel depending on the depth of the corresponding 3D point in the scene.
In many stereo vision applications, it is important to know the depths of objects in a scene. The depth information for a stereo frame or image is typically computed from the disparities between the pixels in the left image and corresponding pixels in the right image because depth is proportional to the reciprocal of the disparity. One technique used for disparity determination that may be used in stereo vision applications is the semi-global matching (SGM) technique described in H. Hirschmuller, “Accurate and Efficient Stereo Processing by Semi-Global Matching and Mutual Information,” IEEE Computer Science Conference on Computer Vision and Pattern Recognition, Vol. 2, Jun. 20-25, 2005, pp. 807-814 (Hirschmuller herein) and H. Hirschmuller, “Stereo Processing by Semi-Global Matching and Mutual Information,” IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 30, No. 2, February 2008, pp. 328-341 (Hirschmuller 2008 herein), which are incorporated by reference herein. This technique provides results that are qualitatively comparable to global matching techniques with reduced computational complexity.